1. Field of the Invention
This invention relates to an endoscope including a bending section.
2. Description of the Related Art
Endoscopes generally include a bending section at the distal end of the insertion section inserted into a body cavity, and flexible endoscopes or rigid endoscopes, each having a bending section, such as a bending lever operated to bend the bending section, at the operation section coupled to the insertion section. In the small diameter flexible endoscopes, such as bronchoscopes inserted into the bronchi, a bending section is provided at the distal end of a small diameter flexible tubular section, and a distal end rigid section is provided at the distal end of the endoscope. In the flexible tubular section, a metal mesh tube (braid) is mounted on an outer circumferential surface of a metal helical tube (flex), and a resin outer coat is mounted on the outer circumferential surface of the metal mesh tube. Therefore, the flexible tubular section can be flexibly bent according to a shape of an insertion path.
In the bending section, a plurality of bending pieces is collaterally arranged in the central axis direction of the insertion section. One end of operation wires are coupled to a distal end of a most distal end bending piece among the bending pieces. The other end of the operation wires extend toward the operation section and are coupled to the bending operation section, such as a bending lever. Wire guides through the wire are placed in the flexible tubular section. Distal ends of the wire guides are secured to the distal end of the flexible tubular section. As the bending lever is rotated, the operation wire is pulled, applying a traction force to the most distal bending piece. The bending pieces of the bending section are therefore turned around their each rotation axis. The bending section is thereby arched as a whole. The illumination window, the observation window and the opening of the instrument insertion channel provided at the distal end rigid section are therefore directed in any desired direction.
Jpn. Pat. Appln. KOKAI Publication No. 2007-61377 discloses a configuration in which a flexible section being shorter than the bending section and able to bend in any desired direction is provided between the distal end rigid section and the bending section, and a flexible-section bending means for bending the flexible section is provided in the operation section. Herein, the flexible-section bending means bends the flexible section by a remote-control. If it receives an external force, the flexible section remains rigid and is not bendable, or the flexible section can be bent according to the external force, when the remote-control of the flexible-section bending means is not performed. Hence, the flexible section can be switched to any one of three states, i.e., bendable by the flexible-section bending means, not bendable by the flexible-section bending means, and freely bendable if it receives an external force.
Jpn. Pat. Appln. KOKAI Publication No. 2003-116779 discloses an endoscope having a flexible tubular section that can be changed in stiffness. A wire and a coil are inserted into the flexible tubular section. In the flexible tubular section, a distal end of the wire is secured at a proximal end of the bending section. In the flexible tubular section, a distal end of the coil is secured adjacent to the distal end of the wire, and a proximal end of the coil is prevented by a coil stopper from moving backwards. The proximal end of the wire extending backwards from the rear end of the coil is pulled, as a rigidity adjusting knob is rotated at the operation section. At the same time, the wire stopper provided at the rear end of the coil is moved as the rigidity adjusting knob is rotated. So moved, the coil is compressed, thus the rigidity of the flexile tubular section is adjusted.